diff --git a/src/deserialize.rs b/src/deserialize.rs
new file mode 100644
index 0000000..952651d
--- /dev/null
+++ b/src/deserialize.rs
@@ -0,0 +1,30 @@
+use std::time::Duration;
+
+use serde::{de::Error, Deserialize, Deserializer};
+
+pub(crate) fn into_duration_ms<'de, D>(deserializer: D) -> std::result::Result<Duration, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let value = serde_json::Number::deserialize(deserializer)?;
+    match value.as_u64() {
+        Some(i) => Ok(Duration::from_millis(i)),
+        None => Err(Error::custom("cannot convert value to u64")),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+
+    use super::*;
+
+    #[test]
+    fn into_duration_ms_ok() {
+        let input = json!(123);
+
+        let got = into_duration_ms(input).expect("value should be deserialized");
+
+        assert_eq!(got, Duration::from_millis(123));
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 08f1d60..d1e01e0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,7 @@
 #![deny(clippy::all, clippy::pedantic, unsafe_code)]
 
 mod backend;
+mod deserialize;
 mod error;
 mod nu;
 use backend::Backend;
diff --git a/src/nu.rs b/src/nu.rs
index ab703ac..c291118 100644
--- a/src/nu.rs
+++ b/src/nu.rs
@@ -178,6 +178,7 @@ pub(crate) struct IdeSettings {
     pub hints: IdeSettingsHints,
     pub include_dirs: Vec<PathBuf>,
     pub max_number_of_problems: u32,
+    #[serde(deserialize_with = "crate::deserialize::into_duration_ms")]
     pub max_nushell_invocation_time: Duration,
     pub nushell_executable_path: PathBuf,
 }